This advisory also applies to the corresponding versions of
Kubuntu, Edubuntu, and Xubuntu.

The problem can be corrected by upgrading your system to the
following package versions:

Ubuntu 9.10:
krb5-kdc 1.7dfsg~beta3-1ubuntu0.1

In general, a standard system upgrade is sufficient to effect the
necessary changes.

Details follow:

Jeff Blaine, Radoslav Bodo, Jakob Haufe, and Jorgen Wahlsten discovered
that the Kerberos Key Distribution Center service did not correctly verify
certain network traffic. An unauthenticated remote attacker could send
a specially crafted request that would cause the KDC to crash, leading
to a denial of service.